Displacement effect of NOM on atrazine adsorption by PACs with different pore size distributions

Qilin Li, Vernon L. Snoeyink, Carlos Campos, Benito J. Mariñas

Research output: Contribution to journalArticlepeer-review


This study investigated displacement of atrazine by the strongly competing fraction of natural organic matter (NOM) in batch and continuous-flow powdered activated carbon (PAC) adsorption systems. Due to the displacement effect, atrazine adsorption capacity in a continuous flow PAC/microfiltration (MF) system, where the carbon retention; time is greater than the hydraulic retention time, decreased with time or NOM throughput. The capacity was lower than that measured in a batch reactor or predicted by the equivalent background compound-ideal adsorbed solution theory (EBC-IAST) method. A mathematical model previously developed to simulate the adsorption process in the PAC/MF system was modified to take into account the displacement effect. Two types of PACs were tested using a range of influent atrazine concentrations and carbon doses. The extent of atrazine displacement by NOM was found to depend on the type of PAC, while the rate of displacement was a function of PAC type as well as carbon dose. The PAC lost its adsorption capacity for atrazine faster at a lower carbon dose. PAC B, which has a higher percentage of mesopores, lost more atrazine adsorption capacity but at a slower rate than PAC A.

Original languageEnglish (US)
Pages (from-to)1510-1515
Number of pages6
JournalEnvironmental Science and Technology
Issue number7
StatePublished - Apr 1 2002

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry


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